This invention relates to an interactive energy absorbing system for a motor vehicle steering column, and more particularly, to an interactive energy absorbing system that adapts to the driver loads as the column collapses.
Energy absorbing steering columns on a motor vehicle generally include a housing that translates linearly through a collapse stroke during a collision. A force generated by the operator from an impact with the steering wheel generates the force to initiate the collapse stroke. The housing moves against a resisting force produced by an energy absorber that converts a portion of the operator""s kinetic energy into work. The resisting force may be generated using several systems known in the art, including the plastic deformation of a metal elementof an energy absorber.
For example, U.S. Pat. No. 3,392,599 discloses an energy absorbing system that utilizes steel spheres that plastically deform the steering column housing by creating tracks in the housing. While the above-referenced design provides for the conversion of kinetic energy of an operator into work by deformation of the steering column housing, the system does not provide varying degrees of resistance based on the force generated by the operator.
An energy absorbing system would ideally convert the kinetic energy of the operator into work at the end of the collapse stroke of the steering column housing. Because designs such as that disclosed in the patent above do not include energy absorbers that are adjustable, optimal energy absorbing performance may not occur for different operators.
Efforts have been made in the art to provide energy absorbing systems that are variable in an effort to achieve a more optimal energy absorbing performance. For example, U.S. Pat. No. 4,886,295 discloses an energy absorbing steering column that includes a plurality of roll deformers positioned in an annulus between the inner tube and a longitudinally split outer tube. An expandable bag containing a fluid is disposed around the outer split tube. A control system varies the fluid pressure within the bag and adjusts the interference fit of the roll deformers between the inner and outer tubes to adjust the energy absorbing characteristics.
While the above-referenced design does include a system that provides for varying energy absorbing performance, the design utilizes complex electronic feedback loops to control the energy absorbing system. There is, therefore, a need in the art for a cost-effective energy absorbing system that does not require electrical inputs and outputs such as sensors and electronically powered motors, but is rather a purely mechanical system. Such a mechanical system would be more cost-effective eliminating the need for costly electronic monitoring systems.
An interactive energy absorbing system including a steering column housing that is moveable along a collapse stroke corresponding to a force of impact by an operator. The interactive energy absorbing system includes an energy absorbing component that exerts a resistance force for resisting movement of the steering column housing along the collapse stroke. The energy absorbing component includes a deformable strap that engages a stationary reaction member and a moveable reaction member. The stationary and moveable reaction members have an adjustable total active surface area for engaging the deformable strap and generating a resistance force. The moveable reaction member moves to adjust the total active surface area due to mechanical translation that corresponds to the force of impact by the operator.
The interactive energy absorbing system of the present invention has the advantage of providing a cost-effective design that does not utilize complex control systems for adjusting the energy absorbing properties of the system.
The interactive energy absorbing system of the present invention has the further advantage of providing an energy absorbing system that is variable according to the force applied to the steering column by the operator. In this manner, many variables such as the weight of the occupant, the speed at which the car is traveling, and other factors contributing to the force generated by the operator are taken into account to generate an optimal resistance force for an individual operator under a specific set of conditions.